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droparea.cpp Example File
draganddrop/dropsite/droparea.cpp

/****************************************************************************
**
** Copyright (C) 2005-2006 Trolltech ASA. All rights reserved.
**
** This file is part of the example classes of the Qt Toolkit.
**
** Licensees holding valid Qt Preview licenses may use this file in
** accordance with the Qt Preview License Agreement provided with the
** Software.
**
** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for
** information about Qt Commercial License Agreements.
**
** Contact info@trolltech.com if any conditions of this licensing are
** not clear to you.
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** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/

#include <QtGui>

#include "droparea.h"

DropArea::DropArea(QWidget *parent)
    : QLabel(parent)
{
    setMinimumSize(200, 200);
    setFrameStyle(QFrame::Sunken | QFrame::StyledPanel);
    setAlignment(Qt::AlignCenter);
    setAcceptDrops(true);
    setAutoFillBackground(true);
    clear();
}

void DropArea::dragEnterEvent(QDragEnterEvent *event)
{
    setText(tr("<drop content>"));
    setBackgroundRole(QPalette::Highlight);

    event->acceptProposedAction();
    emit changed(event->mimeData());
}

void DropArea::dragMoveEvent(QDragMoveEvent *event)
{
    event->acceptProposedAction();
}

void DropArea::dropEvent(QDropEvent *event)
{
    const QMimeData *mimeData = event->mimeData();

    if (mimeData->hasImage()) {
        setPixmap(qvariant_cast<QPixmap>(mimeData->imageData()));
    } else if (mimeData->hasHtml()) {
        setText(mimeData->html());
        setTextFormat(Qt::RichText);
    } else if (mimeData->hasText()) {
        setText(mimeData->text());
        setTextFormat(Qt::PlainText);
    } else {
        setText(tr("Cannot display data"));
    }

    setBackgroundRole(QPalette::Dark);
    event->acceptProposedAction();
}

void DropArea::dragLeaveEvent(QDragLeaveEvent *event)
{
    clear();
    event->accept();
}

void DropArea::clear()
{
    setText(tr("<drop content>"));
    setBackgroundRole(QPalette::Dark);

    emit changed();
}

QPixmap DropArea::extractPixmap(const QByteArray &data, const QString &format)
{
    QList<QByteArray> imageFormats = QImageReader::supportedImageFormats();
    QPixmap pixmap;

    foreach (QByteArray imageFormat, imageFormats) {
        if (format.mid(6) == QString(imageFormat)) {
            pixmap.loadFromData(data, imageFormat);
            break;
        }
    }
    return pixmap;
}


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Qt 4.2.0-rc1